Tinnitus is defined as the perception of sound by an individual when no external sound is present, which is resulted from damage of hair cells in the inner ear or other various diseases.
Currently, 85% of tinnitus are known to be involved in the hair cell damage, which is resulted from traumatic noise, aging, side effects of specific drugs, allergy, inflammation of the outer or middle ear.
Since tinnitus affects daily life as well as mental health of a patient who is suffering from tinnitus, the patient seeks medical intervention including effective treatment. However, in many cases, it is difficult to find out the cause of tinnitus and to treat the tinnitus. Especially, in case of tinnitus caused by hair cell damage, it is more difficult.
In general, tinnitus is diagnosed by subjective judgment of the tinnitus patient, and among the treatment methods are pharmacological treatment, surgery, masking method, and TRT (tinnitus retraining treatment).
In the pharmacological treatment, the drugs for tinnitus treatment could affect neural response of central nervous system or cochlear response in direct/indirect manner. In addition, the drugs can induce some degree of drug tolerance like antidepressants.
Although some drugs such as tranquilizers, antidepressants, and sedatives are known to reduce the severity of tinnitus, the drugs can cause unwanted side effects.
Surgical treatment has a limit on its application because it is performed only for the tinnitus resulted from an abnormality of brain blood system.
Tinnitus masking method uses a noise generator to produce a masking noise, which comprises the same frequency signal as a patient's tinnitus sound and prevents a tinnitus patient from detecting his/her own tinnitus sound.
Tinnitus retraining treatment is a method for habituation of tinnitus and helps a patient to be able to unconsciously ignore the tinnitus sound.
Although both masking method and tinnitus retraining treatment are trying to apply the same signal as patient's tinnitus, in most cases, theses methods fail to accurately diagnose the frequency regions of tinnitus. The reason is that the methods use low-resolution signals that are divided by more than one octave resolution. In addition, the methods take very long time to search the tinnitus frequency region because the diagnosis process including both signal presentation by a specialist and response of a patient should be repeated several times.
Especially, since the masking method should be applied whenever a tinnitus patient detects tinnitus sound, the method is a kind of temporal alternative rather than treatment method.
Additionally, tinnitus retraining treatment may cause damage to the normal hearing region since this method should apply a wide range of noise to the auditory system as long as the low-resolution signals are used for the tinnitus diagnosis.